The report, released by the Fukushima Nuclear Accident Independent Investigation Commission, also warned that the plant may have been damaged by the earthquake on March 11, 2011, even before the arrival of a tsunami — a worrying concern as the quake-prone country starts to bring its reactor fleet back online.
The commission challenged some of the main story lines that the government and the operator of the Fukushima Daiichi Nuclear Power Plant has put forward to explain what went wrong in the early days of the crisis.
"It was a profoundly man-made disaster that could and should have been foreseen and prevented. And its effects could have been mitigated by a more effective human response," Kiyoshi Kurokawa, the commission's chairman and the former head of Tokyo University's Department of Medicine, said in the report's introduction.
But by suggesting that the plant may have sustained extensive damage from the quake — a far more frequent occurrence in Japan — the report in effect casts doubts on the safety of Japan's entire fleet of nuclear plants.